Ischemic ventricular tachycardia (VT) is a contributing cause to more than half of the 300,000 sudden cardiac deaths that occur annually in the United States. Implantable cardioverter defibrillators (ICDs) are the standard therapy but they are expensive the total cost of an ICD implant approaches $50,000 and the United States spends more than $2.2B on these implants annually. ICDs are effective, but not curative up to half of the patients who receive ICDs develop new sites of VT that are unresponsive to the defibrillator, requiring them to be put on antiarrhythmia drugs at additional cost. And 55,000 ICDs have been recalled in the last few years for design and reliability problems. Thermal ablation therapy is an attractive alternative or adjunctive therapy to ICD implantation as it has a success rate of more than 90% for many classes of supraventricular tachycardias, but it has not been successful in treating ischemic VT. It is generally agreed that ablation therapy has been unsuccessful because it is not capable of treating the large, deep arrhythmogenic foci that cause ischemic VT. We have developed a method capable of doing so using saline-enhanced radiofrequency (SERF) ablation. We treat VT by injecting warm saline into the tissue simultaneous with RF ablation. The infused saline flows through the extracellular space convecting energy. This increases the effective thermal conductivity of the tissue by a factor of more than 20. We have used our steerable SERF ablation catheter with a retractable electrode to demonstrate in a canine infarct model that SERF ablation creates thermal lesions large enough to treat VT the lesions are reliably transmural, even in the presence of infarct scars, and multiple lesions can be placed to provide a line of block. We have also shown that the therapy is safe, that the catheter meets safety and reliability requirements, and that it is biocompatible. We propose to complete the development of our saline-enhanced radiofrequency (SERF) ablation system for treating ischemic VT. We will complete the design of our system and catheter and validate that they comply with medical safety standards (EN60601-1), biocompatibility (ISO-10993), and validate the sterilization to a sterility assurance level (SAL) of 10-6. We will carry out extensive preclinical survival testing in large-animal infarct models at the Mayo Clinic, Loyola University, The University of Pennsylvania, and the Brigham and Women's Hospital. We will then apply for and obtain an Investigational Device Exemption (IDE) to carry out a multi-center clinical trial. PUBLIC HEALTH RELEVANCE Our development of SERF ablation to treat ventricular tachycardia (VT) is relevant to public health in that we are addressing a growing and expensive problem the implantable cardioverter defibrillators (ICDs) that patients receive to treat these potentially fatal arrhythmias are neither curative nor reliable. The United States spends over $2B annually placing ICDs, and half of the patients develop additional VTs that are unresponsive to their ICD. At minimum the shocks these patients receive severely reduce their quality of life. At worst the patient remains susceptible to sudden cardiac death. An effective and inexpensive method of treating these patients VTs is urgently needed. [unreadable] [unreadable] [unreadable]